This article is the official HTML5 training tutorial of the H5EDU organization. It mainly introduces: JavaScript enhancement tutorial - jQuery - Obtaining content and attributes
jQuery has a powerful method of manipulating HTML elements and attributes.
jQuery DOM operation
A very important part of jQuery is the ability to operate DOM.
jQuery provides a set of DOM-related methods that make it easy to access and manipulate elements and attributes.
Tip: DOM = Document Object Model
DOM defines the standard for accessing HTML and XML documents:
"The W3C Document Object Model is platform and language independent An interface that allows programs and scripts to dynamically access and update the content, structure, and style of documents."
Getting content - text(), html() and val()
Three simple and practical methods. jQuery methods for DOM manipulation:
text() - Sets or returns the text content of the selected element
html() - Sets or returns the content (including HTML markup) of the selected element
val() - Sets or returns the value of a form field
The following example demonstrates how to obtain content through the jQuery text() and html() methods:
Example
$("#btn1").click(function(){ alert("Text: " + $("#test").text()); }); $("#btn2").click(function(){ alert("HTML: " + $("#test").html()); });
The following example demonstrates how to get the value of an input field through the jQuery val() method:
Example
$("#btn1").click(function(){ alert("Value: " + $("#test").val()); });
Get attributes - attr()
The jQuery attr() method is used to get the attribute value.
The following example demonstrates how to obtain the value of the href attribute in the link:
Example
$("button").click(function(){ alert($("#w3s").attr("href")); });
The above is the JavaScript enhancement tutorial-jQuery - Obtaining content and attributes Content, for more related content, please pay attention to the PHP Chinese website (www.php.cn)!

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JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

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C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

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